The present invention is directed to bicycle brake devices and, more particularly, to bicycle brake devices that are used to brake a hub of a bicycle wheel.
Bicycle braking devices currently available include rim braking devices and hub braking devices. Rim braking devices include cantilever brakes or caliper brakes that brake the rim of the wheel. Hub braking devices brake the wheel hub, and they include drum brakes, band brakes, roller brakes and the like. A hub brake brakes the hub of the wheel, so it is able to provide braking even if the wheel rim is warped.
A drum brake such as a roller brake effects braking by means of friction created when a brake shoe contacts the inside peripheral face (braking surface) of a tubular brake drum that rotates in unison with the wheel hub. In a roller brake, a cam displaces rollers spaced apart in the circumferential direction diametrically outward in order to move a brake shoe against the inner peripheral face of the brake drum. The interior of roller brakes is filled with grease, particularly in the area between the contact surface of the brake shoe and the braking surface. The grease can control the heat produced during braking to improve durability and produce more consistent braking performance. The grease also allows the rollers to move smoothly.
Inconsistent braking performance and braking malfunctions can occur when such conventional hub brake devices run out of grease. The efficient supply of grease between the braking surface and the contact surface is therefore desirable to minimize such malfunctions.